The present invention relates to a turbocharged engine for a vehicle.
A turbocharged engine for a vehicle, in which a small-sized turbocharger, a large-sized turbocharger, and an exhaust-gas purification device are supported at an engine body, is known. Japanese Patent Laid-Open Publication No. 2006-70878, for example, discloses an engine which is arranged laterally so that its crank-shaft direction matches an axel direction of the vehicle, in which the small-sized turbocharger, the large-sized turbocharger, and a DPF (Diesel Particulate Filter) are arranged in back of the engine body in a vehicle longitudinal direction.
In the engine disclosed in the above-described publication, the large-sized turbocharger and DPF are arranged laterally so that their respective axial lines extend in the crank-shaft direction, and arranged almost at the same height position so that they are located side by side in the axial direction on a one-side face of the engine body. Herein, an outlet of a turbine is directly connected to an exhaust inlet of the DPF. The small-sized turbocharger is arranged laterally so that its axial line extends in the crank-shaft direction, and it is located above the DPF (further above the large-sized turbocharger).
An exhaust manifold has two exhaust outlets, and one of them is connected to a turbine of the small-sized turbocharger and the other is connected to a turbine of the large-sized turbocharger via a bypass passage, bypassing the small-sized turbocharger. An exhaust pipe which connects to an outlet of the turbine of the small-sized turbocharger extends upward and then bends downward toward the large-sized turbocharger, and finally connects to the above-described bypass passage.
In case of the above-described turbocharged engine, since the both turbochargers are arranged near the engine body, the loss of exhaust energy is so small that the supercharging function improves. Further, since the DPF is directly connected to the outlet of the turbine of the large-sized turbocharger, the high-temperature exhaust gas is supplied to the DPF so that the regeneration of filter improves.
Herein, while the direct-connection arrangement of the large-sized turbocharger and the DPF, as an exhaust-gas purification device, arranged laterally side by side in the crank-shaft direction has the above-described advantages, in case the size of the exhaust-gas purification device becomes larger, the whole length of the large-sized turbocharger and the DPF in the crank-shaft direction becomes longer, so that both ends of these devices may project greatly from both ends of the engine body. This would cause difficulties in layouts of engine devices, such as a cooling-water pump or alternator, layouts of piping of an air cleaner, intercooler, EGR system and buttery and the like, and in layouts of a master back of a vehicle brake.